The use of autologous free tissue transplantation was pioneered in the 1950s and has since been an important rung in the “reconstructive ladder” commonly described in plastic surgery. This reconstructive ladder is based on the concept of using the simplest technique possible to provide adequate closure or coverage, with increasingly complex techniques employed as needed. The free flap is generally considered the highest and most complex rung of this ladder. Both functional and aesthetic considerations influence a surgeon’s decision to utilize a free flap, often in the setting of postoncologic reconstruction of the head and neck or breast, after traumatic loss of soft tissue, or in facial reanimation procedures. Depending on the nature of the defect, the flap may include innervated muscle, as well as myocutaneous, fasciocutaneous, or osseocutaneous components.

Preoperative evaluation of a patient for a potential free flap reconstruction must consider the patient’s general clinical status and the quality and condition of both the donor and recipient sites. The patient’s nutritional status and age, as well as associated comorbidities such as diabetes, peripheral vascular disease, and cardiovascular disease, are important factors to be weighed when making the assessment. The effect of tobacco use on flap viability is controversial, although it is not an absolute contraindication to creating a free flap. Patients with multiple comorbidities warrant preoperative medical risk stratification.

Specific to the surgical sites, factors to consider are the length of the vascular pedicle, the quality and caliber of recipient vessels, the size match of donor and recipient vessels, the volume and geometry of the flap tissue, and the general condition of the recipient site (prior irradiation, vascular disease, traumatic injury, and infection can affect flap survival).

The most important determinant in graft survival is intraoperative technique. In addition to prophylactic antibiotics, most microvascular surgeons administer either a one-time bolus of 5,000 U of heparin prior to graft harvest or a lower-dose bolus of heparin followed postoperatively by a continuous low-dose infusion. Topical lidocaine or
papaverine is used for vasodilation. Surgical technique should emphasize the delicate handling of vasculature to prevent vasospasm and thrombosis. Excessive traction and drying should be avoided. Vessels should be 1 to 3 mm in diameter, and the ends should be trimmed of loose adventitia. Alignment of the donor and recipient vessels is of utmost importance and is facilitated by ensuring adequate pedicle length (2 to 3 cm), appropriate matching of vessel caliber, and the meticulous placement of interrupted sutures symmetrically and circumferentially. The anastomoses should be free of tension but also of redundancy to prevent kinking and twisting. Flap ischemia time should be minimized, although ischemia times shorter than 3 to 4 hours should not contribute to the risk of flap loss. On insetting the flap, the vascular pedicle should be inspected to ensure the vascular pedicle is not compromised by kinking, twisting, or compression. Postoperatively, patients are often maintained on heparin, dextran, or aspirin, although studies do not conclusively show benefit of any particular regimen.